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How sustainable is geothermal in the UK: getting a measure of fluid and heat flow in Yorkshire’s aquifers

Academic lead
Emma Bramham, Earth and Environment
Arash Rabbani, Computing, Paul Glover, Earth and Environment
Project themes
Environmental Flows, Geophysical and Astrophysical Flows

This project combines mathematical/computational modelling with geological and geophysical parameters to explore fluid and heat flow capacities of potential future geothermal reservoirs within UK aquifers. Using Yorkshire’s aquifers as a focus, the project will examine the relationship between the micro-scale material properties of aquifer rocks and the likely fluid and heat output, recharge and sustainability of these potential geothermal reservoirs. The rocks in Yorkshire’s shallowest 1km produce temperatures that, whilst low enthalpy (below the threshold temperature to produce steam), can be > 50°C providing the potential for a year-round, local energy source for the region. However, to ensure the longevity of any future geothermal reservoir, it is crucial that we have a very good understanding of fluid and heat flow pathways in these aquifer rocks. As such, this project will investigate fluid flow from micro-scale to reservoir scale, using 3D modelling of pore space parameters in Yorkshire’s aquifers. The initial stage will develop 3D micro-scale models representing current in-situ environments using micro-tomography imagery of rock samples. These will be further developed by experimenting with a range of fluid properties, extraction/re-injection rates and pressures, including focus on multi-physical modelling of fluid flow, deposition and heat transfer to simulate the changing environment. Finally, scaling-up to provide potential reservoir scale modelling of fluid flow. 

Figure 1: (a) Map of detected pores labelled by random colours and (b) extracted 2-D network for two typical rock samples. Colours in a) indicate the distinction between two pores (Rabbani et al., 2017). The pathway connecting two pore bodies is known as pore throat. The size of throats depends on the thickness of the connecting pathway between two neighbour pores. Each pore can be schematically replaced by a circle which has the same surface area. By connecting the centres of the neighbour pore bodies the 2-D network of porous media is created, as shown in b).   

Figure 2: Shows the schematics of an Artificial Neural Network (ANN) with 10 hidden layers used to approximate the absolute permeability. The input uses pore network parameters, such as pore size, throat size and length, and porosity, taken from thin section micro-tomography images (Rabbani et al., 2017).  

The project will also benefit from links with the Geothermal Campus project and team, a University of Leeds Geosolutions project that will run for the duration of this project.  

Rabbani, A., Assadi, A., Kharrat, R., Dashti, N. and Ayatollahi, S., 2017. Estimation of carbonates permeability using pore network parameters extracted from thin section images and comparison with experimental data. Journal of Natural Gas Science and Engineering, 42, pp.85-98.